import sys
T = int(sys.stdin.readline())
for _ in range(T):
i, word = sys.stdin.readline().split()
i = int(i)
for n in range(len(word)):
for _ in range(i):
print(word[n], end='')# your code goes here
aW1wb3J0IHN5cwoKVCA9IGludChzeXMuc3RkaW4ucmVhZGxpbmUoKSkKZm9yIF8gaW4gcmFuZ2UoVCk6CiAgICBpLCB3b3JkID0gc3lzLnN0ZGluLnJlYWRsaW5lKCkuc3BsaXQoKQogICAgaSA9IGludChpKQogICAgZm9yIG4gaW4gcmFuZ2UobGVuKHdvcmQpKToKICAgICAgICBmb3IgXyBpbiByYW5nZShpKToKICAgICAgICAgICAgcHJpbnQod29yZFtuXSwgZW5kPScnKSMgeW91ciBjb2RlIGdvZXMgaGVyZQ==